224 SUMMARY OF CURRENT RESEARCHES RELATING TO 



main roots ; and on the other rootlets, its growth was more luxuriant 

 in soil free from humus. He made a series of experiments to deter- 

 mine the species of the fungus ; he does not find that it is identical 

 with any form of Mucor. 



Sporangioles of Endotropic Mycorhiza.* — L.Petri criticises the 

 term sporangiole as applied by Janse to small protuberances on the 

 hyphae of endotropic mycorhiza. They have no connection with the 

 production of spores, and Petri proposes to call them " prosporoidi " 

 for morphological reasons. He examined them in the roots of a number 

 of plants, and was able to produce them on various moulds in artificial 

 cultures, when grown deep down in the substratum. They arise, he 

 holds, on the hyphas, where, in normal conditions, the spores would 

 originate. The contents break up into granules, which in the roots 

 escape into the surrounding protoplasm ; the cells of an old tubercle are 

 full of them ; in cultures they showed no sign of germination. They 

 are formed from the contents of the prosporoid by the agency of a 

 proteolitic enzyme. The writer gives a long account of his observations 

 on endophytic mycorhiza. He has identified the fungus inhabiting the 

 tubercles of Podocarpus as a hyphomycete, Thielaviopsis Podocarpi sp. n., 

 and has cultivated it successfully. It forms two kinds of fructification, 

 macrogonidia— dark-brown gonidia in chains something like a Torula, — 

 and microgonidia, which are produced endogenously in upright hyphge. 



Diseases of Yellow Pine.f — H. von Schrenk describes two forms 

 of fungus disease both following on the attack of a beetle, Dendroclonus 

 ponderosce. The first, causing a bluing of the wood tissue, is due to a 

 Pyrenomycete, Ceratostomella pilifera. Much greater damage is done 

 by the attack of a Polyporus, which causes the wood to turn red. 

 Schrenk considers it a new species, P. ponderosus. 



Injury by Frost followed by Fungoid Attacks.:}: — Sorauer de- 

 scribes the cases in which plants have succumbed to frost and the fungi 

 that are to be found on such plants. Very often they are merely after- 

 growths and have nothing to do with the death of the plant. He gives 

 an account of forms of Alter naria, Ascochyta, Septoria and Cladosporium, 

 which occur in every field of cereals. Fusarium he considers can grow 

 either as a parasite or a saprophyte, and attacks plants under snow. 

 He further discusses the conditions that tend to make frost a danger to 

 the crops. 



Wood-destroying Fungi.§ — P. Hennings writes an account of all 

 the forms that have been found to attack the wood-work of our dwell- 

 ings. Merulius lacrymans is the most frequent and the most harmful, 

 but Polyporus vaporarius is, he says, almost as destructive and as 

 wide-spread. He describes a considerable number that do more or less 

 damage ; nearly all of them Hymenomycetes. There are one or two 

 Ascomycetes in his black list, notably Xylaria polymorpha, and a small 



* App. al Nuovo Giorn. Bot. Ital., x. (1903) pp. 541-62 (5 figs.), and pp. 582-4 

 ;2 figs.). 



t U.S. Dept. of Agric, Bureau of Plant Industry, Bull. No. 36 (1903) 40 pp. and 

 14 pis.). See also Ann. Mycol., i. (1903) pp. 464-5. 



1 Landw. Jalnb., xxxii. pp. 1-titS (4 pis.). See also Centralbl. Bakt., x. (1903) 

 j p. 806-8. § Hedwigia, xlii. (1903) pp. 178-91. 



